Scanning exposure apparatus and method

ABSTRACT

A scanning exposure apparatus for exposing a substrate ( 8 ) to a pattern with an original ( 1 ) through a projection optical system ( 5 ), while scanning the original and the substrate, includes a first detection system ( 14   c ) which detects a first substrate reference mark ( 18   c   1, 18   c   3 ) corresponding to the substrate through the projection optical system on/at at least one of an optical axis of the projection optical and an off-axis position shifted from the optical axis in a scanning direction, and an alignment system ( 2, 9 ) which aligns the original and the substrate on the basis of a detection result of the first detection system.

This application is a divisional application of patent application Ser.No. 10/726,541, filed on Dec. 4, 2003 now U.S. Pat. No. 6,989,885.

FIELD OF THE INVENTION

The present invention relates to a technique for exposing a substrate toa pattern.

BACKGROUND OF THE INVENTION

A conventional scanning exposure apparatus forms and projects the imageof a pattern of an original (reticle or photomask) onto a substrate(wafer) through a projection optical system, and scans (moves) theoriginal and substrate simultaneously with respect to the projectionoptical system.

FIG. 3 is a perspective view showing the schematic arrangement of theconventional scanning exposure apparatus. FIG. 4 is a front view showingthe schematic arrangement of the conventional scanning exposureapparatus.

An original 1 (reticle) is held by an original stage 2 which is drivenin a Y direction in FIG. 3 by a laser interferometer 3 and a drivecontrol means (not shown).

In the vicinity of the original 1, reference originals 4 a and 4 b arefixed within a predetermined range of the original stage 2. Thereflection surfaces of the reference originals 4 a and 4 b are almostflush with the reflection surface of the original 1. A plurality oforiginal reference marks made of a metal such as Cr or Al are formed onthe reflection surfaces of the reference originals 4 a and 4 b servingas reference portions.

The original stage 2 is driven while its position in a Z direction inFIG. 3 is held constant with respect to a projection optical system 5. Amoving mirror 6 which reflects a beam emitted from the laserinterferometer 3 is fixed to the original stage 2. The laserinterferometer 3 measures the position and moving amount of the originalstage 2 successively.

A predetermined pattern formed on the original 1 is illuminated byexposure light emitted from an illumination optical system 7, and isprojected through the projection optical system 5 to form an image on asubstrate 8 (wafer) held by a substrate stage 9.

In the vicinity of the substrate 8, a reference substrate 10 is fixedwithin a predetermined range of the substrate stage 9. The reflectionsurface of the reference substrate 10 is almost flush with the uppersurface of the substrate 8. A plurality of substrate reference marksmade of a metal such as Cr or Al are formed on the reflection surface ofthe reference substrate 10.

The substrate stage 9 has a drive control means (not shown) forrotatably driving the substrate 8 or reference substrate 10 duringvertical driving, image surface blur correction driving, alignment andyawing control of the substrate 8 or reference substrate 10, so that thesubstrate 8 coincides with the image surface of the projection opticalsystem. Furthermore, a moving mirror 12 which reflects a beam from alaser interferometer 11 is fixed to the substrate stage 9. The laserinterferometer 11 measures the position and moving amount of thesubstrate stage 9 successively.

With the above arrangement, the substrate stage 9 can move in thedirection of the optical axis (Z direction) of the projection opticalsystem 5 and within a plane (X-Y plane.) perpendicular to the directionof the optical axis, and can be rotated (θ direction) about the opticalaxis.

The original 1 and substrate 8 are placed at optically conjugatepositions through the projection optical system 5 by a plurality ofposition detection means. The illumination optical system 7 forms aslit-like exposure region or arcuate exposure region elongated in the Xdirection on the original 1. The exposure region on the original 1 formsa slit-like exposure region, having a size substantially proportional tothe projection magnification of the projection optical system 5, on thesubstrate 8.

In the above scanning exposure apparatus, both the original stage 2 andsubstrate stage 9 are driven with respect to the optical path of theexposure light at a speed ratio corresponding to the opticalmagnification of the projection optical system 5, to scan the exposureregion on the original 1 and that on the substrate 8, thus performingscanning exposure.

An oblique incident scheme first position detection means 13 is providedas a focal plane position detection means. The first position detectionmeans 13 irradiates the surface of the substrate 8 (or the surface ofthe reference substrate 10), where the pattern of the original 1 is tobe transferred by the projection optical system 5, in an obliquedirection with non-exposure light, and detects light reflected obliquelyby the surface of the substrate 8 (or the surface of the referencesubstrate 10).

A plurality of position detection light-receiving elements correspondingto the respective reflected beams are provided to the first positiondetection means 13, and are arranged such that the light-receivingsurfaces of the respective position detection light-receiving elementsand the reflection points of the respective beams on the substrate 8 aresubstantially conjugate. Therefore, a positional error of the substrate8 (or reference substrate 10) depending on the direction of the opticalaxis of the projection optical system 5 is measured as a positionalerror of the corresponding position detection light-receiving element ina detection unit.

When, however, the projection optical system 5 absorbs exposure heat orthe ambient atmosphere changes, the focal position of the projectionoptical system 5 changes, and an error occurs in the measurement originand focal plane of the oblique incident scheme first position detectionmeans 13. A second position detection means 14 is loaded to calibratethis error.

As shown in FIG. 3, the second position detection means 14 has a firstposition detection system 14 a and second position detection system 14 bas two position detection systems. The two position detection systems 14a and 14 b extract from the illumination optical system 7 lightcomponents having substantially the same wavelength as that of theexposure light, and guide them through fibers or lens optical systems.The guided light illuminates an in-focus mark on the reference original4 a or 4 b (note that “a reference original 4” includes “the referenceoriginal 4 a or 4 b” unless otherwise specified).

At least one optical system in the second position detection means 14 isdriven in the direction of the detection optical axis, and the detectionfocal plane of the second position detection means 14 is aligned withthe in-focus mark on the reference original 4. Subsequently, thesubstrate stage 9 is vertically driven in the direction of the opticalaxis (Z direction) in the vicinity of the zero point which is preset bythe oblique incident scheme first position detection means 13 inadvance.

During driving, the reference substrate 10 is located substantiallyimmediately under the projection optical system 5. Light transmittedthrough the in-focus mark of the reference original 4 is transmittedthrough the projection optical system 5 to irradiate the referencesubstrate 10. Light reflected by the reference substrate 10 istransmitted through the projection optical system 5 again to becomeincident on the light-receiving portion of the second position detectionmeans 14 through the reference original 4.

The second position detection means 14 has detection ranges for the twoposition detection systems 14 a and 14 b on the X-axis including theoptical path of the exposure light, as shown in FIG. 3, so that themeans 14 estimates the actual exposure image surface from the two, leftand right measurement points on the X-axis. The detection ranges of thefirst and second position detection systems 14 a and 14 b are arrangedsubstantially symmetrically with respect to the optical path of theexposure light. The first and second position detection systems 14 a and14 b are retracted so they do not shield the exposure light duringexposure, and wait at retracted positions away from the exposure region.

The second position detection means 14 also serves as a positiondetection means which detects the positions of the reference original 4and reference substrate 10 relative to each other. The detection resultsserve as elements for calculating the baselines of off-axis microscopes15 and 16. A baseline is the distance between the center of a shot whenaligning the substrate 8 and the center of a shot (optical axis of theprojection optical system) for exposure. The off-axis microscope 15 is anon-TTL (Through The Lens) microscope which uses non-exposure light, andthe off-axis microscope 16 is a TTL microscope which uses non-exposurelight.

The off-axis microscopes 15 and 16 detect the position of an alignmentmark on the substrate 8.

The detection scheme includes a scheme of illuminating the alignmentmark with a laser beam or light emitted from a halogen lamp as a lightsource and having a wide wavelength band, and image-processing the imagedata of the sensed alignment mark, thus measuring the alignment mark, aninterfering alignment scheme of irradiating a diffraction-grating-likealignment mark on the substrate with laser beams having the samefrequency or slightly different frequencies in one or two directions,causing interference between the two diffracted light components, andmeasuring the position of the alignment mark from the phases of the twodiffracted light components, and the like.

The outline of baseline measurement with the off-axis microscopes 15 and16 in the conventional scanning exposure apparatus will be described.

According to baseline measurement of the conventional scanning exposureapparatus, the original stage 2 and substrate stage 9 are driven topredetermined positions, and the positions of the reference original 4and reference substrate 10 relative to each other are detected by thesecond position detection means 14 (first step).

The reference substrate 10 is moved to the detection range of theoff-axis microscope 15 or 16 by driving the substrate stage 9, and theposition of the reference mark formed in the off-axis microscope 15 or16 and the position of the reference mark on the reference substrate 10,which positions are relative to each other, are detected (second step).

The baseline of the off-axis microscope 15 or 16 is calculated from thedetection results of the first and second steps, and the baseline of theoff-axis microscope 15 or 16 is corrected with the calculation result(for example, see Japanese Patent Laid-Open Nos. 9-298147 and 10-79340).

Recently, the patterns of semiconductor integrated circuits are becominglargely integrated and shrinking in size more and more. To furtherimprove the alignment accuracy and throughput of the entire apparatus,an increase in detection processing speed of various types of detectiondevices is required.

According to the prior art as described above, the two positiondetection systems 14 a and 14 b are mounted on the second positiondetection means 14 to perform measurement. This technique advances thelimit for the recent technique of a larger integration degree and asmaller feature size.

During detection of the focal plane position using the second positiondetection means 14, as the actual exposure image surface is estimatedfrom the two, left and right measurement values, the detection ranges ofthe two position detection systems 14 a and 14 b are formed coaxially onthe right and left sides, as described above. Accordingly, with theconventional scanning exposure apparatus, baseline measurement and thelike cannot be performed on the optical path of the exposure light, andmay be adversely affected by distortion or the like caused by theaberration of the projection optical system.

In detection of the focal plane position, measurement must be performedas close as possible to the optical path of the exposure light. Hence,during exposure, the position detection system must be driven to retractfrom the exposure range. The detection time and detection accuracy mayaccordingly be adversely affected by driving.

With the conventional scanning exposure apparatus, since the twoposition detection systems 14 a and 14 b have the detection positionswithin the exposure slit, baseline measurement cannot be performedduring exposure or at an exposure end position. Furthermore, in baselinemeasurement, the original stage 2 and substrate stage 9 must also bedriven to predetermined baseline measurement positions. This poses anissue in the throughput of the entire apparatus.

As the patterns of the semiconductor integrated circuits or the likebecome largely integrated and shrink in size more and more, the NA ofthe projection optical system increases, and the outer shape of theprojection optical system tends to become large. Accordingly, thenon-TTL off-axis microscope provided in the vicinity of the projectionoptical system must be separated from the optical path of the exposurelight. When the baseline becomes long in this manner, the baselinemeasurement accuracy decreases, and the alignment accuracy decreases.

As the wavelength of the exposure light becomes short, the transmittanceof the exposure light with respect to an optical member decreases. Also,the exposure light quantity increases to improve the throughput of theentire apparatus. Therefore, the exposure light absorbed by the originalincreases, causing thermal deformation of the original. The conventionalscanning exposure apparatus, however, does not have any positiondetection system that can detect the thermal deformation of the originalduring exposure.

SUMMARY OF THE INVENTION

In view of the above problems, it is an object of the present inventionto realize at least one of high alignment or overlay accuracy and highthroughput.

In order to solve the above problems and to achieve the above object,according to the present invention, a scanning exposure apparatus forexposing a substrate to a pattern of an original through a projectionoptical system, while scanning the original and the substrate, comprisesa first detection system which detects a first substrate reference markcorresponding to the substrate through the projection optical systemfrom at least one of an on-axis position on an optical axis of theprojection optical and an off-axis position apart from the optical axisin a scanning direction and an alignment system which aligns theoriginal and the substrate based on a detection result of the firstdetection system.

As described above, according to the present invention, at least one ofhigh alignment or high overlay accuracy and high throughput can berealized.

Other objects and advantages besides those discussed above shall beapparent to those skilled in the art from the description of a preferredembodiment of the invention which follows. In the description, referenceis made to accompanying drawings, which form a part thereof, and whichillustrate an example of the invention. Such example, however, is notexhaustive of the various embodiments of the invention, and thereforereference is made to the claims which follow the description fordetermining the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a scanning exposure apparatus accordingto an embodiment of the present invention;

FIG. 2 is a schematic view showing the exposure region, and thedetection region of the second position detection means, of the scanningexposure apparatus according to the embodiment of the present invention;

FIG. 3 is a perspective view of a conventional scanning exposureapparatus;

FIG. 4 is a front view of the conventional scanning exposure apparatus;

FIG. 5 is a layout view of the upper surface of the original stage ofthe scanning exposure apparatus according to the embodiment of thepresent invention;

FIG. 6 is a layout view of the reference substrate marks of the scanningexposure apparatus according to the embodiment of the present invention;

FIGS. 7A and 7B are views for explaining a measurement method in thescanning exposure apparatus according to the embodiment of the presentinvention, in which FIG. 7A is a layout view of the upper surface of theoriginal stage, and FIG. 7B is a front view of the scanning exposureapparatus;

FIGS. 8A and 8B are views for explaining a measurement method in thescanning exposure apparatus according to the embodiment of the presentinvention, in which FIG. 8A is a layout view of the upper surface of theoriginal stage, and FIG. 8B is a front view of the scanning exposureapparatus;

FIGS. 9A and 9B are views for explaining a measurement method in thescanning exposure apparatus according to the embodiment of the presentinvention, in which FIG. 9A is a layout view of the upper surface of theoriginal stage, and FIG. 9B is a front view of the scanning exposureapparatus;

FIGS. 10A and 10B are views for explaining a measurement method in thescanning exposure apparatus according to the embodiment of the presentinvention, in which FIG. 10A is a layout view of the upper surface ofthe original stage, and FIG. 10B is a front view of the scanningexposure apparatus;

FIGS. 11A, 11B, and 11C are views for explaining a measurement method inthe scanning exposure apparatus according to the embodiment of thepresent invention, in which FIG. 11A is a layout view of the uppersurface of the original stage, FIG. 11B is a front view of the scanningexposure apparatus, and FIG. 11C is a layout view of the upper surfaceof a substrate stage;

FIGS. 12A, 12B, and 12C are views for explaining a measurement method inthe scanning exposure apparatus according to the embodiment of thepresent invention, in which FIG. 12A is a layout view of the uppersurface of the original stage, FIG. 12B is a front view of the scanningexposure apparatus, and FIG. 12C is a layout view of the upper surfaceof the substrate stage; and

FIG. 13 is a flow chart showing the flow of an overall semiconductordevice manufacturing process.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Description ofPractical Embodiment

FIG. 1 shows the schematic arrangement of an exposure apparatusaccording to an embodiment of the present invention. For the descriptiveconvenience, the same members as those of the conventional apparatusshown in FIGS. 3 and 4 are denoted by the same reference numerals.

As shown in FIG. 1, in the scanning exposure apparatus of thisembodiment, a first position detection system 14 a, second positiondetection system 14 b, and third position detection system 14 c areprovided as three or more position detection systems to a secondposition detection means 14.

The position detection systems 14 a, 14 b, and 14 c have individualdriving mechanisms for performing detection within arbitrary detectionranges. The first and second position detection systems 14 a and 14 bcan move their detection ranges arbitrarily in a direction (X directionin FIG. 1) substantially perpendicular to the scanning direction of anoriginal stage 2. The third position detection system 14 c can move itsdetection range in a direction (Y direction in FIG. 1) substantiallyparallel to the scanning direction of the original stage 2.

When performing detection using the position detection systems describedabove, one, two or more (a plurality of), or all of arbitrary positiondetection systems can be selected. When calculating the position fromthe detection result of the selected position detection system, one, ortwo or more (a plurality of) detection results can be arbitrarilyselected.

The detection ranges of the first and second position detection systems14 a and 14 b are arranged to be substantially symmetrical with respectto the optical axis of exposure light. The third position detectionsystem 14 c can observe the optical path of the exposure light. Whenexposing the substrate to the pattern of the original, the respectiveposition detection systems 14 a, 14 b, and 14 c are set still atretracted positions where they do not shield the exposure light, or atpositions where they do not shield the exposure light.

As shown in FIG. 2, the scanning exposure apparatus has a shortslit-like or arcuate exposure illumination region 22 (exposure slit) inthe Y direction (the scanning direction of the original stage 2). Sincethe third position detection system 14 c of this embodiment can bedriven to a detection position substantially parallel to the scanningdirection of the original stage 2, it has a detection range 14 ca evenoutside the exposure illumination region (exposure slit) 22, as shown inFIG. 2.

A plurality of position sensors are so provided to the respectiveposition detection systems as not to interfere with them, and arecontrolled by drive control means (not shown).

The second position detection means 14 extracts from an exposureillumination optical system 7 three beams having substantially the samewavelength as that of the exposure light, and guides them to theposition detection systems 14 a, 14 b, and 14 c separately. The threebeams are branched by a method of branching the exposure light intothree beams in the exposure illumination optical system 7, a method ofbranching the exposure light into two beams in the exposure illuminationoptical system 7, further branching one of the two beams in the secondposition detection means 14, and guiding the resultant three beams tothe respective position detection systems, a method of guiding one beamfrom the exposure illumination optical system 7, branching the beam intothree beams in the second position detection means 14, and guiding thethree beams to the respective position detection systems, or the like.

The light guiding method of the scanning exposure apparatus according tothe present invention is not limited to the method described above. Thelight guiding method can have various arrangements not departing fromthe spirit of the present invention as far as it can guide the exposurelight to the respective position detection systems.

The illumination optical system which guides light from the exposureillumination optical system 7 to the second position detection means 14may guide the light through a flexible optical system such as a fiber,or through an optical system such as a lens or mirror. Particularly, ina scanning exposure apparatus that uses a short-wavelength laser such asKrF excimer laser (λ=248 nm), ArF laser (λ=193 nm), or F₂ laser (λ=158nm) as exposure light, the exposure light attenuates largely. Thus, itis effective to guide the light within a space substantially sealed withan inert gas.

The respective position detection systems 14 a, 14 b, and 14 cseparately have attenuation glass members (not shown) capable ofselecting the attenuation rates. Thus, a difference in light quantityamong the position detection systems can be corrected or adjusted.

The number of position detection systems is not limited to three, butthree or more position detection systems can be mounted. Of the three ormore position detection systems, at least two or more, first and secondposition detection systems can move their detection ranges in adirection (the X direction in FIG. 1) substantially perpendicular to thescanning direction of the original stage 2 arbitrarily. Of the remainingposition detection systems, at least one or more third positiondetection systems can move their detection ranges in a direction (the Ydirection in FIG. 1) substantially parallel to the scanning direction ofthe original stage 2. Furthermore, at least one position detectionsystem can observe the optical path of the exposure light.

Each of the position detection systems 14 a, 14 b, and 14 c is not asingle position detection system for the Y- or X-axis shown in FIG. 1,but observes at least one mark on an original 1, reference originals 4 aand 4 b, and a reference substrate 10. Each of the position detectionsystems 14 a, 14 b, and 14 c individually observes the position of themark in the X- and Y-directions.

In each position detection system, a method of detecting the X- andY-axis directions with the same detection optical path, a method ofdetecting the X- and Y-axis directions separately with X- and Y-axisposition detection system optical paths, respectively, or the like canbe employed.

The reference original 4 a has a plurality of original reference marks17 a 1, 17 b 1, 17 c 1, and 17 c 2 which can be detected by therespective position detection systems of the second position detectionmeans 14, with a predetermined known size and interval corresponding tothe detection ranges of the respective position detection systems.

The reference original 4 a shown in FIG. 5 has the original referencemark 17 a 1 which can be observed by the first position detection system14 a, the original reference mark 17 b 1 which can be observed by thesecond position detection system 14 b, and the original reference marks17 c 1 and 17 c 2 which can be observed by the third position detectionsystem 14 c. The distances among the respective original reference marksrelative to each other are set to have known sizes.

The original reference marks 17 a 1, 17 b 1, and 17 c 1 used fordetection using the first, second, and third position detection systems14 a, 14 b, and 14 c are arranged in predetermined detection ranges 14aa and 14 ba, and the detection range 14 ca of the reference original 4a such that their mark array is substantially perpendicular to thescanning direction of the original stage 2.

The original reference marks 17 c 1 and 17 c 2 used for detection usingthe third position detection system 14 c are arranged in the detectionrange 14 ca of the third position detection system 14 c of the referenceoriginal 4 a such that their mark array extends in the scanningdirection along the optical path of the exposure light of the originalstage 2.

The reference original 4 b has the plurality of original reference marks17 a 3, 17 b 3, and 17 c 3 which can be detected by the respectiveposition detection systems of the second position detection means 14,with a predetermined known size and interval in respective detectionranges 14 ab, 14 bb, and 14 cb.

The reference original 4 b shown in FIG. 5 has the original referencemark 17 a 3 which can be observed by the first position detection system14 a, the original reference mark 17 b 3 which can be observed by thesecond position detection system 14 b, and the original reference mark17 c 3 which can be observed by the third position detection system 14c. The distances among the respective original reference marks relativeto each other are set to have known sizes.

The original reference marks 17 a 1 and 17 a 3 are arranged such thattheir mark array is substantially parallel to the scanning direction ofthe original stage 2. Similarly, the original reference marks 17 b 1 and17 b 3; and 17 c 1 and 17 c 3 are arranged such that their mark arraysare substantially parallel to the scanning direction of the originalstage 2.

The original reference marks may be separately, divisionally formed forthe individual position detection systems. When considering the formingaccuracy, the original reference marks are preferably formed on oneplane-parallel glass plate, as shown in FIG. 5. Each original referencemark may include one or a plurality of original reference marks.

The reference substrate 10 serving as the reference portion has aplurality of substrate reference marks 18 a 1, 18 b 1, 18 c 1, 18 a 3,18 b 3, and 18 c 3 which can be detected by the respective positiondetection systems of the second position detection means 14, with apredetermined known size and interval corresponding to the respectivedetection ranges.

The reference substrate 10 shown in FIG. 6 has the substrate referencemarks 18 a 1 and 18 a 3 which can be observed by the first positiondetection system 14 a, the substrate reference marks 18 b 1 and 18 b 3which can be observed by the second position detection system 14 b, andthe substrate reference marks 18 c 1 and 18 c 3 which can be observed bythe third position detection system 14 c. The distances among therespective substrate reference marks relative to each other are set tohave known sizes.

The substrate reference marks 18 a 1, 18 b 1, and 18 c 1 are arrangedsuch that their mark array is substantially parallel to the X-drivingdirection of a substrate stage 9, and are arranged at the predeterminedpositions 14 ac, 14 bc, and 14 cc which can be detected substantiallysimultaneously by the respective position detection systems. Thesubstrate reference marks 18 a 1 and 18 a 3 are set such that their markarray is substantially parallel to the Y-driving direction of thesubstrate stage 9. Similarly, the substrate reference marks 18 b 1 and18 b 3, and 18 c 1 and 18 c 3 are set such that their mark arrays aresubstantially parallel to the Y-driving direction of the substrate stage9.

The reference substrate 10 has a substrate reference mark 19, which canbe detected by an off-axis microscope 15, within a detection range 15 aof the off-axis microscope 15.

The respective substrate reference marks are formed on the respectiveplates on the basis of their designed coordinates, and the relationshipamong their relative positions is known.

In the scanning exposure apparatus of this embodiment, as shown in FIG.1, while the substrate stage 9 is being exposed, the reference substrate10 is preferably located in a range, including the detection range ofthe off-axis microscope 15, between the optical axis of the projectionoptical system 5 and the detection range of the off-axis microscope 15,and the detection range of the third position detection system 14 c withrespect to the reference substrate 10 is preferably located in a range,including the detection range of the off-axis microscope 15, between theoptical axis of the projection optical system 5 and the detection rangeof the off-axis microscope 15. In this case, a large effect can beobtained.

The off-axis microscope 15 in the scanning exposure apparatus accordingto this embodiment has a detection range at a position away from theoptical axis of the projection optical system 5 in the Y-axis scanningdirection.

[First Detection Method]

The scanning exposure apparatus according to this embodiment includes,as the first detection system of the second position detection means 14,a calibration detection method of detecting the origin position of theoriginal stage 2. A measurement example of this method will be described(see FIG. 1 and FIGS. 7A and 7B).

FIGS. 7A and 7B show the detection ranges of the first, second, andthird position detection systems 14 a, 14 b, and 14 c used whenperforming calibration detection described above.

Detection ranges 14 a 1, 14 b 1, and 14 c 1 of the first, second, andthird position detection systems 14 a, 14 b, and 14 c are set on astraight line substantially perpendicular to the scanning direction ofthe original stage 2. The detection range 14 c 1 of the third positiondetection system 14 c substantially coincides with the optical path ofthe exposure light.

Assume that the measurement origin of a laser interferometer 3 is resetbecause, e.g., the apparatus power supply is turned off. When theapparatus power supply is turned on again, the third position detectionsystem 14 c is driven to the detection range 14 c 1 on the optical pathof the exposure light. The original reference mark 17 c 1 on thereference original fixed to the original stage 2 is driven to thedetection range 14 c 1 of the third position detection system 14 c onthe optical path of the exposure light by driving the original stage 2.In this case, the original stage 2 is driven with reference to a sensorprovided to the guide of the original stage 2. The third positiondetection system 14 c detects the error amount between the tube surfacereference (attaching position) of the third position detection system 14c and the reference mark. The origin offset of the original stage 2 iscalculated from this detection result.

The origin offset can be calculated not only from the detection resultof the third position detection system 14 c. Alternatively, the first,second, and third position detection systems 14 a, 14 b, and 14 c may beused, as shown in FIG. 5, and the origin offset may be calculated fromthe respective detection results.

The scanning exposure apparatus according to the present invention candrive an arbitrary position detection system individually, and uses thedetection result of the arbitrary position detection system forcalculating the origin offset. Furthermore, for example, the detectionresults of the respective position detection systems may not be handledequally, but the origin offset may be calculated by placing a specialemphasis on the detection result of the third position detection system14 c which is not influenced by the aberration of the projection lens.

[Second Detection Method]

The scanning exposure apparatus according to this embodiment includes,as the second detection method of the second position detection means14, a detection method of detecting the error amount between therelative position of the optical path of the exposure light and that ofthe reference substrate in baseline measurement of the off-axismicroscope. This measurement example will be described.

First Embodiment

Baseline measurement according to the first embodiment will be describedhereinafter (see FIGS. 1, 5, and 6, and FIGS. 7A and 7B).

To perform this measurement, the third position detection system 14 c isdriven to the third position detection system detection range 14 c 1 onthe optical path of the exposure light.

The original reference mark 17 c 1 formed on the reference original 4 ais moved to the detection range 14 c 1 on the optical path of theexposure light by driving the original stage 2. The substrate referencemark 18 c 1 formed on the reference substrate 10 is moved to thedetection range 14 c 1 on the optical path of the exposure light bydriving the substrate stage 9.

The relative error amount between the original reference mark 17 c 1 andsubstrate reference mark 18 c 1 is detected by the third positiondetection system 14 c (first step). When the first step is completed,the substrate reference mark 19 is moved to the detection range 15 a ofthe off-axis microscope 15. The relative error amount between thesubstrate reference mark 19 and a microscope reference mark 20 which isfixed to the off-axis microscope 15 is detected (second step). Thebaseline of the off-axis microscope 15 is calculated from the detectionresults of the first and second steps, and baseline correction of theoff-axis microscope is performed.

Second Embodiment

According to baseline measurement of the second embodiment (see FIGS. 1,5, and 6, and FIGS. 7A and 7B), when the original reference mark 17 c 1and substrate reference mark 18 c 1 are to be detected by the thirdposition detection system 14 c and the baseline of the off-axismicroscope 15 is to be measured, the relative error amount between theoriginal reference mark 17 a 1 and substrate reference mark 18 a 1 isdetected by the first position detection system 14 a, and the relativeerror amount between the original reference mark 17 b 1 and substratereference mark 18 b 1 is detected by the second position detectionsystem 14 b substantially simultaneously, or separately.

The relative error amount between the original reference mark 17 c 1 andsubstrate reference mark 18 c 1 can be calculated not only from thedetection result of the third position detection system 14 c.

Alternatively, the relative error amount may be detected from thedetection results of the respective position detection systems 14 a, 14b, and 14 c, and the baseline of the off-axis microscope 15 may becalculated at high precision.

The baseline correction of the off-axis microscope 15 is performed byutilizing the above calculation result. Furthermore, the baseline may becalculated not only by handling the detection results of the respectiveposition detection systems 14 a, 14 b, and 14 c equally. Alternatively,the baseline can be calculated by placing an emphasis on the result ofthe third position detection system 14 c which receives the leastinfluence of the aberration of, e.g., the projection optical system 5.

Third Embodiment

Baseline measurement according to the third embodiment will be described(see FIGS. 1, 5, and 6, and FIGS. 8A and 8B).

According to the baseline measurement of the third embodiment, in thethird position detection system 14 c, the wait position during exposureand the detection range substantially coincide.

According to baseline measurement of the third embodiment, as the thirdposition detection system 14 c can perform detection at the retractedposition for exposure, when detection is to be performed by using thethird position detection system 14 c, the third position detectionsystem 14 c need not be driven to the detection position. Therefore, thedriving time and the influence of the driving accuracy of the thirdposition detection system 14 c can be eliminated in baselinemeasurement, so that high-speed, high-accuracy baseline measurement canbe performed. The baseline correction of the off-axis microscope 15 isperformed by utilizing this measurement result.

Assume that the wait position for exposure and the detection range ofthe third position detection system 14 c do not substantially coincidebut are close to each other for a reason such as layout limitation. Evenin this case, since the driving time and the influence of the drivingaccuracy of the third position detection system 14 c decreases, a shortmeasurement time and high measurement accuracy can be expected.

These effects are not limited to baseline measurement, but are obtainedin various types of detection methods that use the third positiondetection system 14 c.

Fourth Embodiment

Baseline measurement according to the fourth embodiment will bedescribed (see FIGS. 1, 5, and 6, and FIGS. 8A and 8B).

According to this embodiment, while the original stage 2 or substratestage 9, or both of them are not moved, the relative error amountbetween the original reference mark 17 c 1 and substrate reference mark18 c 1 is detected by the third position detection system 14 c, and therelative error amount between the substrate reference mark 19 and themicroscope reference mark 20 of the off-axis microscope 15 is detectedby the off-axis microscope 15.

Therefore, baseline measurement that does not require driving of theoriginal stage 2 or substrate stage 9, or both of them is possible, andbaseline measurement in which the driving time or the influence of thedriving accuracy is eliminated or reduced can be performed at high speedand at high accuracy. The baseline correction of the off-axis microscope15 is performed from this measurement result.

Assume that above detection without moving the substrate stage 9 cannotbe performed for a reason such as layout limitation of the periphery ofthe projection optical system 5. In this case, the detection range ofthe third position detection system 14 c may be set between the opticalaxis of the projection optical system 5 and the detection range of theoff-axis microscope 15. Then, when performing baseline measurement, thesubstrate stage position when the third position detection system 14 cis to be used and the substrate stage position when the off-axismicroscope 15 is to be used can be set close to each other. Thus, thedriving amount of the substrate stage 9 can be decreased, so that ashort measurement time and high measurement accuracy can be expected.

Regarding the original stage 2, when performing baseline measurement,the original stage position when the third position detection system 14c is to be used and the original stage position during (at the end of)exposure can be set close to each other. Thus, the same effect as thatdescribed above can be expected.

Fifth Embodiment

Baseline measurement according to the fifth embodiment will be described(see FIGS. 1, 2, 5, and 6, and FIGS. 11A to 11C).

As shown in FIG. 11A, the detection range 14 c 1 of the third positiondetection system 14 c substantially coincides with the detectionpossible range at the wait position for exposure, in the same manner asin the fourth embodiment.

At the exposure end position, the baseline measurement of the off-axismicroscope 15 can be performed without driving the original stage 2,substrate stage 9, or third position detection system 14 c.

The arrangement of this embodiment will be described in detail.

As shown in FIG. 2, the detection range of the third position detectionsystem 14 c is set not only within the exposure illumination region 22but also outside it. Thus, even at the wait position for exposure, thethird position detection system 14 c can perform detection.

When the original stage 2 is scanned in scanning exposure, the originalreference mark 17 c 2 of the reference original 4 a is moved to thedetection range 14 c 1 of the third position detection system 14 c, asshown in FIG. 11A, so that it is arranged within a range where it can bedetected when scanning exposure is ended.

As the substrate stage 9 is scanned in scanning exposure, the substratereference mark 18 c 3 of the reference substrate 10 is arranged in arange where it can be detected by the third position detection system 14c when scanning exposure is ended, as shown in FIG. 11C.

Furthermore, the off-axis microscope 15, the substrate reference mark 19on the reference substrate 10, and the substrate reference mark 18 c 3are arranged such that the substrate reference mark 19 for the off-axismicroscope 15 can be detected by the off-axis microscope 15 whenscanning exposure is ended.

With the above arrangement, at the scanning exposure end position, therelative error amount between the original reference mark 17 c 2 andsubstrate reference mark 18 c 3 is detected by the third positiondetection system 14 c without driving the original stage 2, substratestage 9, or third position detection system 14 c. The relative erroramount between the substrate reference mark 19 and the microscopereference mark 20 which is fixed to the off-axis microscope 15 isdetected. The baseline of the off-axis microscope 15 is calculated fromthese detection results.

According to this embodiment, baseline measurement can be performed atthe exposure end position without driving the original stage 2,substrate stage 9, or third position detection system 14 c. Thus, thethroughput of the entire apparatus can be improved.

Regarding the measurement accuracy, since it does not include theinfluence of driving, high-accuracy detection and calculation can beperformed.

Sixth Embodiment

Baseline measurement according to the sixth embodiment will be described(see FIGS. 1, 2, 5, and 6, and FIGS. 12A to 12C).

As shown in FIG. 12A, the detection range 14 c 1 of the third positiondetection system 14 c substantially coincides with the detectionpossible range at the wait position for exposure. The positions of thereference original 4 a and reference substrate 10 relative to each othercan be detected by the third position detection system 14 c at apredetermined position during exposure. Also, the reference substrate 10can be detected by the off-axis microscope 15.

The arrangement of this embodiment will be described in detail.

As shown in FIG. 2, the detection range of the third position detectionsystem 14 c is set not only within the exposure illumination region 22but also outside it. Thus, the third position detection system 14 ccan-perform detection at the wait position for exposure.

When the original stage 2 is scanned in scanning exposure, the originalreference mark 17 c 2 of the reference original 4 a is moved to thedetection range 14 c 1 of the third position detection system 14 c, asshown in FIG. 12A, so that it is arranged within a range where it can bedetected in a predetermined range during scanning exposure.

As the substrate stage 9 is scanned in scanning exposure, the substratereference mark 18 c 3 of the reference substrate 10 is arranged in arange where it can be detected by the third position detection system 14c in a predetermined range during scanning exposure, as shown in FIG.12C.

Furthermore, at this substrate stage position, the substrate referencemark 19 for the off-axis microscope 15 can be detected by the off-axismicroscope 15.

With the above arrangement, in a predetermined range during scanningexposure, the relative error amount between the original reference mark17 c 2 and substrate reference mark 18 c 3 is detected by the thirdposition detection system 14 c, and the relative error amount betweenthe substrate reference mark 19 and the microscope reference mark 20which is fixed to the off-axis microscope 15 is detected. The baselineof the off-axis microscope 15 is calculated from these detectionresults. According to this embodiment, the calculation result of thebaseline during exposure can be sent to an arithmetic processing unit(not shown), so that a correction process or correction driving ofcorrecting fluctuation of the baseline during exposure can be performed.

Conventionally, baseline measurement is performed after exposure isended. According to this embodiment, baseline measurement can beperformed or started before exposure is ended. Thus, the throughput ofthe entire apparatus can be improved.

High-accuracy baseline measurement of the off-axis microscope 16 whichis not influenced by the movement of the detection system or stage canbe performed.

As shown in FIGS. 9A and 9B, in baseline measurement or the like of thescanning exposure apparatus of this embodiment, not the referenceoriginal 4 a, but the reference original 4 b or original 1 can be used.

[Third Detection Method]

The scanning exposure apparatus according to this embodiment includes,as the third detection method of the second position detection means, amethod of measuring a difference in travel between the original stage 2and substrate stage 9 (see FIGS. 1, 5, and 6, and FIGS. 7A and 7B).

The original reference marks 17 a 3, 17 b 3, and 17 c 3 are moved to thedetection ranges of the first, second, and third position detectionsystems 14 a, 14 b, and 14 c by driving the original stage 2.Substantially simultaneously, the substrate reference marks 18 a 1, 18 b1, and 18 c 1 are moved by driving the substrate stage 9. The relativeerror amounts between the original reference marks 17 a 3, 17 b 3, and17 c 3 and the substrate reference marks 18 a 1, 18 b 1, and 18 c 1 aremeasured by the respective position detection systems, and therespective reference marks are aligned (third step).

The original reference marks 17 a 1, 17 b 1, and 17 c 1 are moved to thedetection ranges of the first, second, and third position detectionsystems 14 a, 14 b, and 14 c by driving the original stage 2. Therelative error amounts between the original reference marks 17 a 1, 17 b1, and 17 c 1 and the substrate reference marks 18 a 1, 18 b 1, and 18 c1 are measured by the respective position detection systems (fourthstep).

The substrate reference marks 18 a 3, 18 b 3, and 18 c 3 are moved tothe detection ranges of the first, second, and third position detectionsystems 14 a, 14 b, and 14 c by driving the substrate stage 9. Therelative error amounts between the original reference marks 17 a 1, 17 b1, and 17 c 1 and the substrate reference marks 18 a 3, 18 b 3, and 18 c3 are measured by the respective position detection systems (fifthstep).

The original reference marks 17 a 3, 17 b 3, and 17 c 3 are moved to thedetection ranges of the first, second, and third position detectionsystems 14 a, 14 b, and 14 c by driving the original stage 2. Therelative error amounts between the original reference marks 17 a 3, 17 b3, and 17 c 3 and the substrate reference marks 18 a 3, 18 b 3, and 18 c3 are measured by the respective position detection systems (sixthstep).

A difference in travel between the original stage 2 and substrate stage9 is calculated from the results of the third to sixth steps. Thedifference in travel between the original stage 2 and substrate stage 9is corrected with the calculation result.

[Fourth Detection Method]

The scanning exposure apparatus according to this embodiment includes,as the fourth detection method of the second position detection means, amethod of measuring the tilt (e.g., the rotational position (θ) aboutthe optical axis of the projection optical system) of the original 1with respect to the original stage 2 (see FIGS. 1, 5, and 6, and FIGS.10A and 10B).

When performing this measurement, the relative positions of the original1 and the reference mark which is fixed to the original stage 2 (notshown) are calculated by a microscope (not shown).

A plurality of mark groups 1 a, 1 b, and 1 c that can be detected by therespective position detection systems of the second position detectionmeans 14 are formed on the original 1, which is to be used for thismeasurement, with a predetermined known size and interval correspondingto the respective detection ranges.

The mark groups 1 a, 1 b, and 1 c which can be observed by the first,second, and third position detection systems 14 a, 14 b, and 14 c,respectively, are formed on the original 1 shown in FIG. 10A. The markarrays of the respective mark groups are substantially parallel to eachother, and their relative distances have known sizes.

The first measurement marks of the mark groups 1 a, 1 b, and 1 c aremoved to the respective detection ranges of the first, second, and thirdposition detection systems 14 a, 14 b, and 14 c by driving the originalstage 2. Substantially simultaneously, the substrate reference marks 18a 1, 18 b 1, and 18 c 1 are moved by driving the substrate stage 9. Therelative error amounts between the first measurement marks and thesubstrate reference marks 18 a 1, 18 b 1, and 18 c 1 are measured by therespective position detection systems.

The original stage 2 is scanned to observe the plurality of markpositions of the respective mark groups, so that the relative erroramounts between the plurality of mark positions and the substratereference marks 18 a 1, 18 b 1, and 18 c 1 are measured. The tilt of theoriginal 1 with respect to the original stage 2 is calculated from thedetection results of the relative error amounts of the respective marks,the calculation results of the relative positions of the original 1 andthe reference marks fixed to the original stage (not shown), and thecalculation results of the travels of the original stage 2 and substratestage 9 detected by the third detection method.

[Fifth Detection Method]

The scanning exposure apparatus according to this embodiment includes,as the fifth detection method of the second position detection means 14,a method of detecting the thermal deformation of a reticle duringexposure (see FIGS. 1, 5, and 6, and FIGS. 9A and 9B).

With the scanning exposure apparatus according to this embodiment, thethird position detection system 14 c can observe the reference substrate10 even at the wait position during exposure. One or a plurality ofmarks to be used for this measurement are formed on the original 1.Similarly, one or a plurality of marks to be used for this measurementare formed also on the reference substrate 10. During exposure of anyone shot of the shot arrays when the exposure shot array comes theclosest to the reference substrate 10, or during movement of thesubstrate stage 9 among shots, one or the plurality of marks on theoriginal and the marks on the reference substrate can be detected byoverlaying.

With this detection, the thermal deformation amount of the reticleduring exposure is calculated from a change in distances among theplurality of marks, in mark positions on the original 1 with referenceto the marks on the reference substrate 10, or in shapes of the marks. Aprocess of compensating for the thermal deformation of the reticle isperformed on the basis of the calculation result.

Effect of the Embodiment

According to this embodiment, the third position detection system 14 cis newly provided to the second position detection means 14. Thus,compared to the conventional case wherein detection is performed withthe two position detection systems 14 a and 14 b, high-accuracycalculation of the origin offset of the substrate stage 9, andhigh-accuracy position measurement in, e.g., baseline measurementconcerning the off-axis microscope 15 or an off-axis microscope 16,measurement of the relative travel error between the original stage 2and substrate stage 9, and tilt measurement of the original 1 withrespect to the original stage 2, can be performed.

The third position detection system 14 c can perform detection on theoptical axis of the projection optical system with light havingsubstantially the same wavelength as that of the exposure light throughthe projection optical system. Thus, high-accuracy position detectioncan be performed.

In baseline measurement or the like, since the third position detectionsystem 14 c can perform measurement at the wait position for exposurewithout moving the substrate stage, it can perform high-speed positiondetection. Simultaneously, since a driving error can be eliminated orreduced, high-accuracy position detection can be performed.

The detection position of the third position detection system 14 c islocated not only within the exposure region but also outside it. Thus,in baseline measurement or the like, the original stage 2 need not bedriven, or the driving amount of the original stage 2 can be reduced, sothat the throughput of the apparatus can be improved. Simultaneously,since the driving error can be eliminated or reduced, high-accuracyposition detection can be performed.

The detection position of the third position detection system 14 c islocated not only within the exposure region but also outside it. Thus,in baseline measurement or the like, the third position detection system14 c need not be driven, or the driving amount of the third positiondetection system 14 c can be reduced, so that the throughput of theentire apparatus can be improved. Simultaneously, since the drivingerror can be eliminated or reduced, high-accuracy position detection canbe performed.

The detection range of the third position detection system 14 c islocated between the optical path of the exposure light and the detectionrange of the off-axis microscope 15 (including the two ends). Thus, inbaseline measurement, the driving amount for driving the original stage2 or substrate stage 9, or both of them can be reduced or eliminated,and high-speed, high-accuracy position detection can be performed. Thus,the throughput of the apparatus can be improved, and high-accuracyoverlaying exposure can be performed.

Baseline measurement concerning the off-axis microscope 15 or 16 can beperformed without moving the original stage 2 or substrate stage 9, orboth of them, and the detection range of the third position detectionsystem 14 c from the exposure end positions. Therefore, high-speed,high-accuracy position detection can be performed, so that thethroughput of the apparatus can be improved, and high-accuracyoverlaying exposure can be performed.

Base measurement or the like can be performed during exposure by usingthe third position detection system 14 c. Thus, the throughput of theapparatus can be improved.

The deformation amount of the reticle caused by exposure heat or thelike can be detected by using the third position detection system 14 c.Thus, high-accuracy overlaying exposure can be performed.

[Device Manufacturing Method]

A process of manufacturing a semiconductor device as an example of adevice such as a microdevice by utilizing this exposure apparatus willbe described. FIG. 13 shows the flow of the overall semiconductor devicemanufacturing process. In step 1 (circuit design), circuit design of thesemiconductor device is performed. In step 2 (mask fabrication), a maskis fabricated on the basis of the designed circuit pattern.

In step 3 (wafer fabrication), a wafer is manufactured using a materialsuch as silicon. In step S4 (wafer process) called a preprocess, anactual circuit is formed on the wafer by lithography with the aboveexposure apparatus using the prepared mask and wafer. In step S5(assembly) called a post-process, a semiconductor chip is formed fromthe wafer fabricated in step S5. This step includes processes such asassembly (dicing and bonding) and packaging (chip encapsulation). Instep S6 (inspection), inspections including operation check test anddurability test of the semiconductor device manufactured in step 5 areperformed. A semiconductor device is completed with these processes, andshipped in step S7.

The wafer process of step S4 includes the following steps: an oxidationstep of oxidizing the surface of the wafer, a CVD step of forming aninsulating film on the wafer surface, an electrode formation step offorming an electrode on the wafer by deposition, an ion implantationstep of implanting ions into the wafer, a resist processing step ofapplying a photosensitive agent to the wafer, an exposure step oftransferring the circuit pattern onto the wafer after the resistprocessing step by the exposure apparatus, a developing step ofdeveloping the wafer exposed in the exposure step, an etching step ofetching portions other than the resist image developed in the developingstep, and a resist peeling step of removing any unnecessary resistremaining after etching. By repeating these steps, a multilayeredstructure of circuit patterns is formed on the wafer.

Other Embodiment

The above embodiments are realized when the program of software thatrealizes a function such as measurement or compensation function of theabove embodiments is supplied to the system or the apparatus directly,or by remote control, and the computer of the system or apparatus readsand performs the supplied program code. In this case, the embodimentneed not be a program as far as it retains the function of the program.

Therefore, to realize the function and process of the present inventionwith the computer, the program code itself which is to be installed inthe computer can constitute the embodiment of the present invention.

In this case, the program can take any shape, e.g., an object code, aprogram which is to be performed by an interpreter, or script data to besupplied to the OS, as far as it retains the function of the program.

A recording medium used for supplying the program can be, e.g., aflexible disk, a hard disk, an optical disk, a magneto-optical disk, anMO, a CD-ROM, a CD-R, a CD-RW, a magnetic tape, a nonvolatile memorycard, a ROM, a DVD (DVD-ROM, DVD-R), or the like.

A method of supplying the program includes allowing the user to connectto a homepage on the Internet using the browser of the client computer,and to download a computer program itself, or a compressed filecontaining an automatic installation function from the homepage to arecording medium such as a hard disk. Also, the program codeconstituting the program of the present invention can be divided into aplurality of files, and the respective files can be downloaded fromdifferent homepages. In other words, a WWW server for allowing aplurality of users to download a program file that realizes the functionand process of the present invention with a computer can also constitutethe embodiment of the present invention.

The program can be encrypted and stored in a storage medium such as aCD-ROM. The storage medium can be distributed to the user. A user whosatisfies predetermined conditions can be allowed to download keyinformation for decryption from a homepage through the Internet. Theuser can decrypt the program by using the key information, and caninstall the decrypted program in the computer.

The OS or the like running on the computer may perform part or all ofthe actual process in response to the commands of the program. Forexample, when the computer performs the readout program, the function ofthe embodiment described above is realized. The function of theembodiment described above may be realized by this process.

Furthermore, the program read out from the recording medium may bewritten in a memory provided to a function expansion board inserted inthe computer or a function expansion unit connected to the computer.After that, a CPU or the like provided to the function expansion boardor function extension unit may perform part or all of the actualprocess. The function of the embodiment described above may be realizedby this process.

The present invention is not limited to the above embodiments andvarious changes and modifications can be made within the spirit andscope of the present invention. Therefore, to apprise the public of thescope of the present invention the following claims are made.

1. An exposure apparatus for performing an exposure of a substrate to apattern of an original while the original and the substrate are scannedin a scanning direction, said apparatus comprising: an original stageconfigured to hold the original and to move; a projection optical systemconfigured to project light from the original onto the substrate; and afirst detector configured to move in the scanning direction separatelyfrom said original stage and to detect a position of a first substratereference mark corresponding to the substrate through said projectionoptical system, said first detector being configured to detect theposition of the first substrate reference mark from a selective one ofan on-axis position on an optical axis of said projection optical systemand an off-axis position apart from the optical axis in the scanningdirection, wherein the original and the substrate are aligned based onthe position of the first substrate reference mark detected by saidfirst detector.
 2. An apparatus according to claim 1, further comprisinga substrate stage configured to hold the substrate and to move, whereinthe first substrate reference mark is formed on said substrate stage. 3.An apparatus according to claim 1, wherein said first detector isconfigured to detect a positional error between an original referencemark corresponding to the original and the first substrate referencemark.
 4. An apparatus according to claim 1, further comprising a seconddetector configured to detect a position of a second substrate referencemark corresponding to the substrate through said projection opticalsystem from an off-axis position apart from the optical axis in adirection perpendicular to the scanning direction.
 5. An apparatusaccording to claim 1, wherein the original and the substrate are alignedbased on the position of the first substrate reference mark detected bysaid first detector and the position of the second substrate referencemark detected by said second detector.
 6. An apparatus according toclaim 1, further comprising a non-TTL off-axis microscope configured todetect a position of a non-TTL off-axis substrate reference markcorresponding to the substrate, not through said projection opticalsystem.
 7. An apparatus according to claim 6, wherein a correction valuewith respect to said non-TTL off-axis microscope is calculated based onthe position of the first substrate reference mark detected by saidfirst detector and the position of the non-TTL off-axis substratereference mark detected by said non-TTL off-axis microscope.
 8. Anapparatus according to claim 1, further comprising a TTL off-axismicroscope configured to detect a position of a TTL off-axis substratereference mark corresponding to the substrate, through said projectionoptical system.
 9. An apparatus according to claim 8, wherein acorrection value with respect to said TTL off-axis microscope iscalculated based on the position of the first substrate reference markdetected by said first detector and the position of the TTL off-axissubstrate reference mark detected by said TTL off-axis microscope. 10.An apparatus according to claim 1, wherein an origin offset of saidoriginal stage is calculated based on the position of the firstsubstrate reference mark detected by said first detector.
 11. Anapparatus according to claim 3, wherein a difference in travel betweenthe original and the substrate is corrected based on the positionalerror detected by said first detector.
 12. An apparatus according toclaim 1, wherein said first detector is configured to detect apositional error between a measurement mark formed on the original andthe first substrate reference mark.
 13. An apparatus according to claim12, wherein a rotational position of the original with respect to theoptical axis of said projection optical system is calculated based onthe positional error detected by said first detector.
 14. An apparatusaccording to claim 1, wherein said first detector is configured todetect the first substrate reference mark from the off-axis positionduring exposure.
 15. An apparatus according to claim 14, furthercomprising a non-TTL off-axis microscope configured to detect a thirdnon-TTL off-axis substrate reference mark corresponding to thesubstrate, not through said projection optical system, wherein saidnon-TTL off-axis microscope is configured to detect the non-TTL off-axissubstrate reference mark with respect to the same position of thesubstrate as the position with respect to which said first detectordetects the first substrate reference mark.
 16. An apparatus accordingto claim 15, wherein a correction value with respect to said non-TTLoff-axis microscope is calculated based on the position of the firstsubstrate reference mark detected by said first detector and theposition of the non-TTL off-axis substrate reference mark detected bysaid non-TTL off-axis microscope.
 17. An apparatus according to claim 1,wherein said first detector is configured to detect the first substratereference mark using having a wavelength, which is substantially thesame as a wavelength of light used for the exposure.
 18. An apparatusaccording to claim 1, further comprising a third detector configured todetect a third substrate reference mark corresponding to the substrate,through said projection optical system from an off-axis position apartfrom the optical axis in a direction perpendicular to the scanningdirection, wherein said first, second and third detectors are configuredto detect the first, second and third substrate reference marks usinglight having a wavelength, which is substantially the same as awavelength of light used for the exposure, respectively.
 19. A method ofmanufacturing a device, said method comprising steps of: exposing asubstrate to a pattern of an original using an exposure apparatus asdefined in claim 1; developing the exposed substrate; and processing thedeveloped substrate to manufacture the device.
 20. An apparatusaccording to claim 1, wherein said first detector is configured todetect a mark formed on the original from the off-axis position duringthe exposure, and a deformation amount of the original is calculatedbased on the position of the mark formed on the original detected bysaid first detector.